An apparatus for purifying exhaust gas for an internal combustion engine equipped with an HC adsorbent, which is capable of adsorbing HC and moisture contained in the exhaust gas and which is disposed in a bypass passage bypassing a main exhaust passage, has been disclosed in the past, for example, by Patent Document 1. The conventional exhaust gas purifying apparatus supplies the exhaust gas into the bypass passage at the cold start to adsorb HC and the moisture by the HC adsorbent, thereby preventing HC that cannot be purified by a catalyst before the catalyst is activated from being released into the atmosphere. Furthermore, the conventional exhaust gas purifying apparatus, after the warm-up of the catalyst is completed, supplies hot exhaust gas into the HC adsorbent to desorb HC and the moisture from the HC adsorbent. As a result, HC and the moisture are flown back into an intake system.
In addition, the conventional exhaust gas purifying apparatus switches a flow target into which the exhaust gas flows between the main exhaust passage and the bypass passage on the basis of a temperature of the exhaust gas at a downstream side of the HC adsorbent.
Including the above-mentioned document, the applicant is aware of the following documents as a related art of the present invention.    [Patent Document 1] Japanese Laid-open Patent Application Publication No. 2002-138820    [Patent Document 2] Japanese Laid-open Patent Application Publication No. 2000-345832